They’re comparing a 45 mpg car to a 65 mpg car I believe, I think they’re just re reporting this press release. Still sounds a little low though, some back of the napkin math assuming gas is $3/gallon would still suggest you’d save that much after only like 30,000 miles. Savings would be more if you drove your car further than that over its life or if gas was more expensive.

https://www.nhtsa.gov/press-releases/new-fuel-economy-standards-model-years-2027-2031

The Washington post article and the nhsta press release are confusing, 50 mpg isn’t the standard, that’s just the average mpg for the mix of cars and trucks they expect to be sold in 2031.

The standards are increasing to 65 mpg for cars over time (there are yearly increases that gradually get there) and 45 mpg for light trucks/suvs. Heavy trucks and vans are also getting higher percent increases in required mpg average, though begining from a lower floor. The mix of all of the vehicle classes bring sold together will average to 50 mpg, which is where the Washington post gets that number.

Nyt article and the actual rule draft both have a lot more details.

https://www.nytimes.com/2024/06/07/climate/biden-mileage-electric-vehicles.html

https://www.nhtsa.gov/sites/nhtsa.gov/files/2024-06/CAFE-2027-2031-HDPUV-2030-2035_Final-Rule_web_0.pdf